The invention relates to a drum for a chopping device, in particular a precision chipper, comprising a shaft on which the drum is arranged, wherein at the outer circumference of the drum cutting tools are provided in blade holders serving for chopping the material to be chopped, having at least one distancing piece comprising a support surface or contact surface for the material to be chopped on the drum, the height of which distancing piece determining the chip size of the chopping process.
Drums of this kind are known in precision chippers that have become known either as chopping cylinder, knife drum, flail drum, or chopping drum. These drums are mounted in a housing and can be set for rotational movement. These chopping machines are employed, for example, in forestry for chopping wood scraps. However, they also serve for chopping food or cellulose material. When using precision chippers the focus is on even chips in a certain dimension. Preferably different chip sizes can be produced for different materials to be chopped with one device. In the state of the art it is known that the knives are height-adjustable, i. e. their flight circle can change. Because of the wear of the knives, however, after a short processing time the size of the chips change, and this is not desired. What is also known are precision chippers having a drum with one or more supports serving as a distancing piece or a distance holder for the material to be chopped. However, it is a disadvantage of these devices that the size of the chips cannot be changed. It is another disadvantage of these devices that the distance holder is exposed to a very high wear when used as intended.
In the citation DE 10 2005 053 006 B3 a chopping rotor with adjustable cutting depth is described. As it can already be seen in the drawing, wedge 4 can be height-adjusted continuously. It can be swiveled around an axis. However, the disadvantage of this device is the fact that the chip size can change unintentionally even when used as intended.